列车阻塞下类矩形隧道烟流特性研究

Study on smoke flow characteristics of rectangular tunnel under train blocking

为研究类矩形隧道中地铁列车阻塞情况下的烟气运动特性,利用FDS软件,分析有、无列车两种工况下类矩形隧道中烟气蔓延、温度分布以及临界风速的变化规律。结果表明,无列车堵塞时,火源与隧道顶棚间距较大,空间高度对火焰燃烧的抑制效果不明显,出现受浮力影响的羽流;有列车堵塞时,受车厢顶棚阻挡会出现双侧线性羽流。无列车堵塞时,烟气温度最大值位于火源上方,火源两侧依次降低;有列车堵塞时,高温区始终位于隧道顶棚两侧,且隧道顶棚左侧由于存在弧形结构,温度稍高于右侧。当热释放速率不大于7.5 MW时,临界风速与其呈正相关;当热释放速率大于7.5 MW时,临界风速受热释放速率的影响逐渐变小;临界风速会随着阻塞比增大而减小。因此,精准探测列车停靠位置,优化通风排烟方式,可达到最佳的效果。

In order to study the smoke movement characteristics under the condition of metro train obstruction in rectangular tunnel,this paper uses FDS to analyze the smoke spread,temperature distribution and critical velocity change in rectangular tunnel under the two working conditions.The results show that when there is no train blockage,the distance between the fire source and the tunnel ceiling is large,the effect of space height on flame combustion is not obvious,and the plume affected by buoyancy appears;When there is train blockage,there will be linear plumes on both sides blocked by the car roof.When there is no train blockage,the maximum smoke temperature is located above the fire source,and the two sides of the fire source decrease in turn;When the train is blocked,the high temperature zone is always located on both sides of the tunnel roof,and the temperature on the left side of the tunnel roof is slightly higher than the temperature on the right side of the tunnel roof due to the arc structure.When the heat release rate is not greater than 7.5 MW,the critical wind speed is positively correlated with it;When the heat release rate is greater than 7.5 MW,the influence of the critical wind speed on the heat release rate gradually decreases;The critical wind speed will decrease with the increase of blocking ratio.Therefore,the best effect can be achieved by accurately detecting the train stop position and optimizing the ventilation and smoke exhaust mode.